diff --git a/runtime/lua/vim/filetype.lua b/runtime/lua/vim/filetype.lua
index a17d6dd03d..8bc7c1f05d 100644
--- a/runtime/lua/vim/filetype.lua
+++ b/runtime/lua/vim/filetype.lua
@@ -696,7 +696,7 @@ local extension = {
   lex = 'lex',
   lxx = 'lex',
   ['l++'] = 'lex',
-  l = 'lex',
+  l = detect_seq('lex', detect.nroff),
   lhs = 'lhaskell',
   lidr = 'lidris2',
   ly = 'lilypond',
@@ -835,6 +835,7 @@ local extension = {
   nix = 'nix',
   norg = 'norg',
   nqc = 'nqc',
+  ['0'] = detect.nroff,
   ['1'] = detect.nroff,
   ['2'] = detect.nroff,
   ['3'] = detect.nroff,
@@ -844,6 +845,24 @@ local extension = {
   ['7'] = detect.nroff,
   ['8'] = detect.nroff,
   ['9'] = detect.nroff,
+  ['0p'] = detect.nroff,
+  ['1p'] = detect.nroff,
+  ['3p'] = detect.nroff,
+  ['1x'] = detect.nroff,
+  ['2x'] = detect.nroff,
+  ['3x'] = detect.nroff,
+  ['4x'] = detect.nroff,
+  ['5x'] = detect.nroff,
+  ['6x'] = detect.nroff,
+  ['7x'] = detect.nroff,
+  ['8x'] = detect.nroff,
+  ['3am'] = detect.nroff,
+  ['3perl'] = detect.nroff,
+  ['3pm'] = detect.nroff,
+  ['3posix'] = detect.nroff,
+  ['3type'] = detect.nroff,
+  n = detect.nroff,
+  o = detect.nroff,
   roff = 'nroff',
   tmac = 'nroff',
   man = 'nroff',
@@ -1390,7 +1409,7 @@ local extension = {
   pp = detect.pp,
   i = detect.i,
   w = detect.progress_cweb,
-  p = detect.progress_pascal,
+  p = detect_seq(detect.nroff, detect.progress_pascal),
   pro = detect_seq(detect.proto, 'idlang'),
   patch = detect.patch,
   r = detect.r,
diff --git a/runtime/lua/vim/filetype/detect.lua b/runtime/lua/vim/filetype/detect.lua
index c2674febc6..0497181cf7 100644
--- a/runtime/lua/vim/filetype/detect.lua
+++ b/runtime/lua/vim/filetype/detect.lua
@@ -1175,7 +1175,7 @@ end
 --- @type vim.filetype.mapfn
 function M.nroff(_, bufnr)
   for _, line in ipairs(getlines(bufnr, 1, 5)) do
-    if line:find('^%.') then
+    if line:find('^%.%S%S?') then
       return 'nroff'
     end
   end
diff --git a/test/old/testdir/test_filetype.vim b/test/old/testdir/test_filetype.vim
index 9affc308ee..035beed869 100644
--- a/test/old/testdir/test_filetype.vim
+++ b/test/old/testdir/test_filetype.vim
@@ -2918,6 +2918,20 @@ func Test_map_file()
   filetype off
 endfunc
 
+func Test_nroff_file()
+  filetype on
+
+  call writefile(['.TH vim 1 "YYYY Mth DD"'], 'Xfile.1', 'D')
+  split Xfile.1
+  call assert_equal('nroff', &filetype)
+  bwipe!
+
+  call writefile(['. /etc/profile'], 'Xfile.1', 'D')
+  split Xfile.1
+  call assert_notequal('nroff', &filetype)
+  bwipe!
+endfunc
+
 func Test_org_file()
   filetype on